In situ observation of polymer blend phase separation by x-ray Talbot-Lau interferometer

Abstract

Talbot interferometer using white synchrotron radiation has been demonstrated for time-resolved X-ray phase imaging and tomography as well as four-dimensional phase tomography to observe dynamics in samples. In this study, X-ray phase tomography has been used to follow the time evolution of phase separation in polymer blend through heating treatment. For this purpose, we performed in-situ X-ray phase imaging and tomography with X-ray Talbot-Lau interferometer using white synchrotron radiation. The X-ray Talbot-Lau interferometer consisted of a source grating (30 μm in period), a π/2 phase grating (4.5 μm in period), an amplitude grating (5.3 μm in period) and a high-speed camera. A polymer blend sample of polystyrene (PS) (Mw = 76,500) and polymethyl methacrylate (PMMA) (Mw = 33,200) was used for the CT observation. A compound of the PS and PMMA was made by a twin-screw kneading extruder and put into an Al tube whose inner diameter was 6 mm. The sample temperature was maintained at desired temperature sequence by controlling a lamp for heating, and CT scans were repeated to track the changes in sample structures at a temporal resolution of 5 seconds. PS-rich phase and PMMA-rich phase changing with time evolution were revealed.